Object's body descriptors refactoring.

src/objects-body-descriptors-inl.h

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
+#define V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
+
+#include "src/objects-body-descriptors.h"
+
+namespace v8 {
+namespace internal {
+
+template <int start_offset>
+int FlexibleBodyDescriptor<start_offset>::SizeOf(Map* map, HeapObject* object) {
+  return object->SizeFromMap(map);
+}
+
+
+bool BodyDescriptorBase::IsValidSlotImpl(HeapObject* obj, int offset) {
+  if (!FLAG_unbox_double_fields || obj->map()->HasFastPointerLayout()) {
+    return true;
+  } else {
+    DCHECK(FLAG_unbox_double_fields);
+    DCHECK(IsAligned(offset, kPointerSize));
+
+    LayoutDescriptorHelper helper(obj->map());
+    DCHECK(!helper.all_fields_tagged());
+    return helper.IsTagged(offset);
+  }
+}
+
+template <typename ObjectVisitor>
+void BodyDescriptorBase::IterateBodyImpl(HeapObject* obj, int start_offset,
+                                         int end_offset, ObjectVisitor* v) {
+  if (!FLAG_unbox_double_fields || obj->map()->HasFastPointerLayout()) {
+    IteratePointers(obj, start_offset, end_offset, v);
+  } else {
+    DCHECK(FLAG_unbox_double_fields);
+    DCHECK(IsAligned(start_offset, kPointerSize) &&
+           IsAligned(end_offset, kPointerSize));
+
+    LayoutDescriptorHelper helper(obj->map());
+    DCHECK(!helper.all_fields_tagged());
+    for (int offset = start_offset; offset < end_offset;) {
+      int end_of_region_offset;
+      if (helper.IsTagged(offset, end_offset, &end_of_region_offset)) {
+        IteratePointers(obj, offset, end_of_region_offset, v);
+      }
+      offset = end_of_region_offset;
+    }
+  }
+}
+
+
+template <typename StaticVisitor>
+void BodyDescriptorBase::IterateBodyImpl(Heap* heap, HeapObject* obj,
+                                         int start_offset, int end_offset) {
+  if (!FLAG_unbox_double_fields || obj->map()->HasFastPointerLayout()) {
+    IteratePointers<StaticVisitor>(heap, obj, start_offset, end_offset);
+  } else {
+    DCHECK(FLAG_unbox_double_fields);
+    DCHECK(IsAligned(start_offset, kPointerSize) &&
+           IsAligned(end_offset, kPointerSize));
+
+    LayoutDescriptorHelper helper(obj->map());
+    DCHECK(!helper.all_fields_tagged());
+    for (int offset = start_offset; offset < end_offset;) {
+      int end_of_region_offset;
+      if (helper.IsTagged(offset, end_offset, &end_of_region_offset)) {
+        IteratePointers<StaticVisitor>(heap, obj, offset, end_of_region_offset);
+      }
+      offset = end_of_region_offset;
+    }
+  }
+}
+
+
+template <typename ObjectVisitor>
+void BodyDescriptorBase::IteratePointers(HeapObject* obj, int start_offset,
+                                         int end_offset, ObjectVisitor* v) {
+  v->VisitPointers(HeapObject::RawField(obj, start_offset),
+                   HeapObject::RawField(obj, end_offset));
+}
+
+
+template <typename StaticVisitor>
+void BodyDescriptorBase::IteratePointers(Heap* heap, HeapObject* obj,
+                                         int start_offset, int end_offset) {
+  StaticVisitor::VisitPointers(heap, obj,
+                               HeapObject::RawField(obj, start_offset),
+                               HeapObject::RawField(obj, end_offset));
+}
+
+
+template <typename ObjectVisitor>
+void BodyDescriptorBase::IteratePointer(HeapObject* obj, int offset,
+                                        ObjectVisitor* v) {
+  v->VisitPointer(HeapObject::RawField(obj, offset));
+}
+
+
+template <typename StaticVisitor>
+void BodyDescriptorBase::IteratePointer(Heap* heap, HeapObject* obj,
+                                        int offset) {
+  StaticVisitor::VisitPointer(heap, obj, HeapObject::RawField(obj, offset));
+}
+
+
+// Iterates the function object according to the visiting policy.
+template <JSFunction::BodyVisitingPolicy body_visiting_policy>
+class JSFunction::BodyDescriptorImpl final : public BodyDescriptorBase {
+ public:
+  STATIC_ASSERT(kNonWeakFieldsEndOffset == kCodeEntryOffset);
+  STATIC_ASSERT(kCodeEntryOffset + kPointerSize == kNextFunctionLinkOffset);
+  STATIC_ASSERT(kNextFunctionLinkOffset + kPointerSize == kSize);
+
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    if (offset < kSize) return true;
+    // TODO(ishell): v8:4531, fix when JFunctions are allowed to have
+    // in-object properties
+    // return IsValidSlotImpl(obj, offset);
+    return true;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IteratePointers(obj, kPropertiesOffset, kNonWeakFieldsEndOffset, v);
+
+    if (body_visiting_policy & kVisitCodeEntry) {
+      v->VisitCodeEntry(obj->address() + kCodeEntryOffset);
+    }
+
+    if (body_visiting_policy & kVisitNextFunction) {
+      IteratePointers(obj, kNextFunctionLinkOffset, kSize, v);
+    }
+
+    // TODO(ishell): v8:4531, fix when JFunctions are allowed to have in-object
+    // properties
+    // IterateBodyImpl(obj, kSize, object_size, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IteratePointers<StaticVisitor>(heap, obj, kPropertiesOffset,
+                                   kNonWeakFieldsEndOffset);
+
+    if (body_visiting_policy & kVisitCodeEntry) {
+      StaticVisitor::VisitCodeEntry(heap, obj,
+                                    obj->address() + kCodeEntryOffset);
+    }
+
+    if (body_visiting_policy & kVisitNextFunction) {
+      IteratePointers<StaticVisitor>(heap, obj, kNextFunctionLinkOffset, kSize);
+    }
+
+    // TODO(ishell): v8:4531, fix when JFunctions are allowed to have in-object
+    // properties
+    // IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    // TODO(ishell): v8:4531, fix when JFunctions are allowed to have in-object
+    // properties
+    return JSFunction::kSize;
+  }
+};
+
+
+class JSArrayBuffer::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  STATIC_ASSERT(kByteLengthOffset + kPointerSize == kBackingStoreOffset);
+  STATIC_ASSERT(kBackingStoreOffset + kPointerSize == kBitFieldSlot);
+  STATIC_ASSERT(kBitFieldSlot + kPointerSize == kSize);
+
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    if (offset < kBackingStoreOffset) return true;
+    if (offset < kSize) return false;
+    if (offset < kSizeWithInternalFields) return true;
+    // TODO(ishell): v8:4531, fix when JSArrayBuffers are allowed to have
+    // in-object properties
+    // return IsValidSlotImpl(obj, offset);
+    return true;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IteratePointers(obj, kPropertiesOffset, kBackingStoreOffset, v);
+    IteratePointers(obj, kSize, kSizeWithInternalFields, v);
+
+    // TODO(ishell): v8:4531, fix when JSArrayBuffers are allowed to have
+    // in-object properties
+    // IterateBodyImpl(obj, kSize, object_size, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IteratePointers<StaticVisitor>(heap, obj, kPropertiesOffset,
+                                   kBackingStoreOffset);
+    IteratePointers<StaticVisitor>(heap, obj, kSize, kSizeWithInternalFields);
+
+    // TODO(ishell): v8:4531, fix when JSArrayBuffers are allowed to have
+    // in-object properties
+    // IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    // TODO(ishell): v8:4531, fix when JSArrayBuffers are allowed to have
+    // in-object properties
+    // return map->instance_size();
+    return kSizeWithInternalFields;
+  }
+};
+
+
+class BytecodeArray::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    return offset == kConstantPoolOffset;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IteratePointer(obj, kConstantPoolOffset, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IteratePointer<StaticVisitor>(heap, obj, kConstantPoolOffset);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    return SizeFor(
+        reinterpret_cast<FixedArray*>(object)->synchronized_length());
+  }
+};
+
+
+class FixedTypedArrayBase::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    return offset == kBasePointerOffset;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IteratePointer(obj, kBasePointerOffset, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IteratePointer<StaticVisitor>(heap, obj, kBasePointerOffset);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    return reinterpret_cast<FixedTypedArrayBase*>(object)->size();
+  }
+};
+
+
+class JSWeakCollection::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    // TODO(ishell): v8:4531, fix when JSWeakCollections are allowed to have
+    // in-object properties
+    // return IsValidSlotImpl(obj, offset);
+    return true;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IteratePointers(obj, kPropertiesOffset, kSize, v);
+
+    // TODO(ishell): v8:4531, fix when JSWeakCollections are allowed to have
+    // in-object properties
+    // IterateBodyImpl(obj, kSize, object_size, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IteratePointers<StaticVisitor>(heap, obj, kPropertiesOffset, kSize);
+
+    // TODO(ishell): v8:4531, fix when JSWeakCollections are allowed to have
+    // in-object properties
+    // IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
+};
+
+
+class Foreign::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    v->VisitExternalReference(reinterpret_cast<Address*>(
+        HeapObject::RawField(obj, kForeignAddressOffset)));
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    StaticVisitor::VisitExternalReference(reinterpret_cast<Address*>(
+        HeapObject::RawField(obj, kForeignAddressOffset)));
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
+};
+
+
+class ExternalOneByteString::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    typedef v8::String::ExternalOneByteStringResource Resource;
+    v->VisitExternalOneByteString(reinterpret_cast<Resource**>(
+        HeapObject::RawField(obj, kResourceOffset)));
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    typedef v8::String::ExternalOneByteStringResource Resource;
+    StaticVisitor::VisitExternalOneByteString(reinterpret_cast<Resource**>(
+        HeapObject::RawField(obj, kResourceOffset)));
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
+};
+
+
+class ExternalTwoByteString::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    typedef v8::String::ExternalStringResource Resource;
+    v->VisitExternalTwoByteString(reinterpret_cast<Resource**>(
+        HeapObject::RawField(obj, kResourceOffset)));
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    typedef v8::String::ExternalStringResource Resource;
+    StaticVisitor::VisitExternalTwoByteString(reinterpret_cast<Resource**>(
+        HeapObject::RawField(obj, kResourceOffset)));
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
+};
+
+
+class Code::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  STATIC_ASSERT(kRelocationInfoOffset + kPointerSize == kHandlerTableOffset);
+  STATIC_ASSERT(kHandlerTableOffset + kPointerSize ==
+                kDeoptimizationDataOffset);
+  STATIC_ASSERT(kDeoptimizationDataOffset + kPointerSize ==
+                kTypeFeedbackInfoOffset);
+  STATIC_ASSERT(kTypeFeedbackInfoOffset + kPointerSize == kNextCodeLinkOffset);
+
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    // Slots in code can't be invalid because we never trim code objects.
+    return true;
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, ObjectVisitor* v) {
+    int mode_mask = RelocInfo::kCodeTargetMask |
+                    RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
+                    RelocInfo::ModeMask(RelocInfo::CELL) |
+                    RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
+                    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE) |
+                    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE_ENCODED) |
+                    RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
+                    RelocInfo::kDebugBreakSlotMask;
+
+    IteratePointers(obj, kRelocationInfoOffset, kNextCodeLinkOffset, v);
+    v->VisitNextCodeLink(HeapObject::RawField(obj, kNextCodeLinkOffset));
+
+    RelocIterator it(reinterpret_cast<Code*>(obj), mode_mask);
+    Isolate* isolate = obj->GetIsolate();
+    for (; !it.done(); it.next()) {
+      it.rinfo()->Visit(isolate, v);
+    }
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IterateBody(obj, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj) {
+    int mode_mask = RelocInfo::kCodeTargetMask |
+                    RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
+                    RelocInfo::ModeMask(RelocInfo::CELL) |
+                    RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
+                    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE) |
+                    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE_ENCODED) |
+                    RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY) |
+                    RelocInfo::kDebugBreakSlotMask;
+
+    Heap* heap = obj->GetHeap();
+    IteratePointers<StaticVisitor>(heap, obj, kRelocationInfoOffset,
+                                   kNextCodeLinkOffset);
+    StaticVisitor::VisitNextCodeLink(
+        heap, HeapObject::RawField(obj, kNextCodeLinkOffset));
+
+    RelocIterator it(reinterpret_cast<Code*>(obj), mode_mask);
+    for (; !it.done(); it.next()) {
+      it.rinfo()->template Visit<StaticVisitor>(heap);
+    }
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    IterateBody<StaticVisitor>(obj);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    return reinterpret_cast<Code*>(object)->CodeSize();
+  }
+};
+
+
+template <typename Op, typename ReturnType, typename T1, typename T2,
+          typename T3>
+ReturnType BodyDescriptorApply(InstanceType type, T1 p1, T2 p2, T3 p3) {
+  if (type < FIRST_NONSTRING_TYPE) {
+    switch (type & kStringRepresentationMask) {
+      case kSeqStringTag:
+        return ReturnType();
+      case kConsStringTag:
+        return Op::template apply<ConsString::BodyDescriptor>(p1, p2, p3);
+      case kSlicedStringTag:
+        return Op::template apply<SlicedString::BodyDescriptor>(p1, p2, p3);
+      case kExternalStringTag:
+        if ((type & kStringEncodingMask) == kOneByteStringTag) {
+          return Op::template apply<ExternalOneByteString::BodyDescriptor>(
+              p1, p2, p3);
+        } else {
+          return Op::template apply<ExternalTwoByteString::BodyDescriptor>(
+              p1, p2, p3);
+        }
+    }
+    UNREACHABLE();
+    return ReturnType();
+  }
+
+  switch (type) {
+    case FIXED_ARRAY_TYPE:
+      return Op::template apply<FixedArray::BodyDescriptor>(p1, p2, p3);
+    case FIXED_DOUBLE_ARRAY_TYPE:
+      return ReturnType();
+    case JS_OBJECT_TYPE:
+    case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
+    case JS_GENERATOR_OBJECT_TYPE:
+    case JS_MODULE_TYPE:
+    case JS_VALUE_TYPE:
+    case JS_DATE_TYPE:
+    case JS_ARRAY_TYPE:
+    case JS_TYPED_ARRAY_TYPE:
+    case JS_DATA_VIEW_TYPE:
+    case JS_SET_TYPE:
+    case JS_MAP_TYPE:
+    case JS_SET_ITERATOR_TYPE:
+    case JS_MAP_ITERATOR_TYPE:
+    case JS_ITERATOR_RESULT_TYPE:
+    case JS_REGEXP_TYPE:
+    case JS_GLOBAL_PROXY_TYPE:
+    case JS_GLOBAL_OBJECT_TYPE:
+    case JS_MESSAGE_OBJECT_TYPE:
+      return Op::template apply<JSObject::BodyDescriptor>(p1, p2, p3);
+    case JS_WEAK_MAP_TYPE:
+    case JS_WEAK_SET_TYPE:
+      return Op::template apply<JSWeakCollection::BodyDescriptor>(p1, p2, p3);
+    case JS_ARRAY_BUFFER_TYPE:
+      return Op::template apply<JSArrayBuffer::BodyDescriptor>(p1, p2, p3);
+    case JS_FUNCTION_TYPE:
+      return Op::template apply<JSFunction::BodyDescriptor>(p1, p2, p3);
+    case ODDBALL_TYPE:
+      return Op::template apply<Oddball::BodyDescriptor>(p1, p2, p3);
+    case JS_PROXY_TYPE:
+      return Op::template apply<JSProxy::BodyDescriptor>(p1, p2, p3);
+    case JS_FUNCTION_PROXY_TYPE:
+      return Op::template apply<JSFunctionProxy::BodyDescriptor>(p1, p2, p3);
+    case FOREIGN_TYPE:
+      return Op::template apply<Foreign::BodyDescriptor>(p1, p2, p3);
+    case MAP_TYPE:
+      return Op::template apply<Map::BodyDescriptor>(p1, p2, p3);
+    case CODE_TYPE:
+      return Op::template apply<Code::BodyDescriptor>(p1, p2, p3);
+    case CELL_TYPE:
+      return Op::template apply<Cell::BodyDescriptor>(p1, p2, p3);
+    case PROPERTY_CELL_TYPE:
+      return Op::template apply<PropertyCell::BodyDescriptor>(p1, p2, p3);
+    case WEAK_CELL_TYPE:
+      return Op::template apply<WeakCell::BodyDescriptor>(p1, p2, p3);
+    case SYMBOL_TYPE:
+      return Op::template apply<Symbol::BodyDescriptor>(p1, p2, p3);
+    case BYTECODE_ARRAY_TYPE:
+      return Op::template apply<BytecodeArray::BodyDescriptor>(p1, p2, p3);
+
+    case HEAP_NUMBER_TYPE:
+    case MUTABLE_HEAP_NUMBER_TYPE:
+    case SIMD128_VALUE_TYPE:
+    case FILLER_TYPE:
+    case BYTE_ARRAY_TYPE:
+    case FREE_SPACE_TYPE:
+      return ReturnType();
+
+#define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size) \
+  case FIXED_##TYPE##_ARRAY_TYPE:                       \
+    return Op::template apply<FixedTypedArrayBase::BodyDescriptor>(p1, p2, p3);
+      TYPED_ARRAYS(TYPED_ARRAY_CASE)
+#undef TYPED_ARRAY_CASE
+
+    case SHARED_FUNCTION_INFO_TYPE: {
+      return Op::template apply<SharedFunctionInfo::BodyDescriptor>(p1, p2, p3);
+    }
+
+#define MAKE_STRUCT_CASE(NAME, Name, name) case NAME##_TYPE:
+      STRUCT_LIST(MAKE_STRUCT_CASE)
+#undef MAKE_STRUCT_CASE
+      if (type == ALLOCATION_SITE_TYPE) {
+        return Op::template apply<AllocationSite::BodyDescriptor>(p1, p2, p3);
+      } else {
+        return Op::template apply<StructBodyDescriptor>(p1, p2, p3);
+      }
+    default:
+      PrintF("Unknown type: %d\n", type);
+      UNREACHABLE();
+      return ReturnType();
+  }
+}
+
+
+template <typename ObjectVisitor>
+void HeapObject::IterateFast(ObjectVisitor* v) {
+  BodyDescriptorBase::IteratePointer(this, kMapOffset, v);
+  IterateBody(v);
+}
+
+
+template <typename ObjectVisitor>
+void HeapObject::IterateBodyFast(ObjectVisitor* v) {
+  Map* m = map();
+  IterateBody(m->instance_type(), SizeFromMap(m), v);
+}
+
+
+struct CallIterateBody {
+  template <typename BodyDescriptor, typename ObjectVisitor>
+  static void apply(HeapObject* obj, int object_size, ObjectVisitor* v) {
+    BodyDescriptor::IterateBody(obj, object_size, v);
+  }
+};
+
+template <typename ObjectVisitor>
+void HeapObject::IterateBodyFast(InstanceType type, int object_size,
+                                 ObjectVisitor* v) {
+  BodyDescriptorApply<CallIterateBody, void>(type, this, object_size, v);
+}
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_OBJECTS_BODY_DESCRIPTORS_INL_H_